Regulating system



Patented Oct. 19, 1937 UNITED STATES REGULATING SYSTEM Finn H. Gulliksen, Wilkinsburg, Pa., assignor to Westinghouse Electri c 8; Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 12, 1934, Serial No. 757,238

6 Claims.

My invention relates to electrical regulating and control apparatus, and it has particular relation to control systems in which a light-sensitive device is utilized to abruptly and for a predetermined short period change the current supplied to a solenoid or other type of actuating mechanism.

Systems of this type are useful in a number of industrial and other applications wherein an interrup'tion'or an establishment of a light beam is' arranged to detect predetermined unusual or undesired conditions and to actuate equipment adapted to eifect the correction or compensation thereof. Past systems of this type have required that there be interposed between the photo tube and the current-responsive actuator which it controls, time delay relay means, of the movable part or mechanical contact variety, in combination with one or more electronic-tube devices.

Generally stated, an object of my invention is to simplify this intermediate or interposed equipment and to render its operation more precise and effective.

Another object of my invention is to provide a control circuit in which no mechanical or other type of relay device is required to eifect the desired time delay operation features.

An additional object is to so arrange the elec- 30 tronic-tube control circuits that following each impulse from the light sensitive device the tube will automatically return itself to a non-con-g ductive state upon the expiration of a given time interval appropriate for the.particular control 35 application.

A further object is to provide a system of the type above characterized in which the length of this time interval may be adjusted throughout a relatively wide range.

In practicing my invention I utilize, between the photo tube and the actuator which it controls, an electronic tube of the gas-filled, gridcontrolled type which is energized from a source of direct current supply. In shunt relation with 45 the majorelements of the tube I connect a capacitor which, when the tube is in the normally non-conductive state, is charged to the full tube energizing potential. When the photo tube receives a light impulse proper to render the gas- 50 filled tube conductive and thereby effect an operation of the actuating mechanism to be controlled, the capacitor dissipates its charge through the tube. When the capacitor voltage attains a value below that required to maintain u current flow through the tube, the tube is ren- (Cl. Z50-41.5)

dered non-conductive and effects a release of the actuating mechanism. By proper correlation of the capacitor with other elements of the con-v trol circuit of. which it forms a part, the period of tube conductivity may be adjusted through out a wide range of values.

MU invention itself, together with additional objects and advantages thereof will best be understood through the following description of specific embodiments when taken in conjunction with the accompanying drawing in which:

Figure 1 is a diagrammatic view of apparatus and circuits illustrating the improved control means of my invention applied to a can sorting machine;

Fig. 2 is a view in side elevation of the conveyor, the can-withdrawing mechanism and the photo-cell and its illuminating lamp;

Fig. 3 is a sectional view taken on line IlI-lII of Fig. 1 showing further details of the can-withdrawing mechanism;

Fig. 4 is a diagrammatic view of a modied control circuit combination in which the photo tube is arranged to control the actuating mechanism in response to an interruption of the light beam; and

Fig. 5 illustrates further circuit modications showing how the actuating mechanism may be adapted for control in response to a current flow therethrough. i

Referring to Figs. 1, 2 and 3 of the drawing, my invention is there depicted in association with a traveling conveyor l0 upon which cans or other articles I2 are fed for deliveryto suitable receiving equipment (not shown). 'I'he majority of these receptacles are of similar size or character; however, from time to time one or more of different variety, indicated at I4, may find its way to the conveyor, and it is desired that these be removed therefrom before being delivered with those of the uniform variety indicated at i2.

For the purpose of effecting such removal, I have indicated a yole structure I6 normally held in the position indicated in Fig. 1 by a solenoid device I8 which acts against a tension spring 20. An interruption of the energizing current of this solenoid, shown as being supplied thereto through a circuit which includes a unidirectional source of voltage 22 and a controlling electronic tube 24, allows this spring to withdraw the yoke I6 which removes the odd sized can Il from the conveyor. This current interruption must, of course, be initiated at a time when this odd sized can is underneath the yoke as is shown in' the drawing, and must be discontinued as soon as removal Las been effected in order that the yoke may return to the illustrated position before the can next in line moves in line therewith.

In the system of Figs. 1, 2 and 3, a light beam supplied from a light source 26 is directed upon each of the cans as it moves into the position registering with the yoke and if it strikes a bright or reecting surface, as in the case of the can I4, it is reiiected upon a photo tube 28 which functions, in a. manner to be explained, to eiect a withdrawal of the can from the c onveyor. In order that the cans of the desired character may not thus reflect the light beam, they may be covered, as indicated in Fig. 2, with dark colored paint which extends to an elevation above the point 30 at which the beam contacts them. The cans of other sizes are not so rendered non-refleeting and therefore serve to ash light upon the photocell whenever they come into line with the light beam i Between the photo cell and the actuating device control tube 24, which is illustrated as of the triode-vacuum or continuous-control type, is interposed an electronic tube 32 which is of the gas-filled or non-continuous-control variety. The photo tube and this electronic tube have associated with them control circuits which are energized from a source of unidirectional potential shown in the form of a battery 34. The photo tube is energized by the full-voltage of this source through a circuit which includes a resistor 36 WhileA the gas-filled tube 32 has impressed between the major elements thereof only a portion of the source voltage through a circuit which includes a resistor 38 and the right hand portion of a voltage dividing resistor 40. The left hand portion of this resistor is connected to maintain the grid element 42 of the tube at a potential which is negative with respect to the cathode element thereof.

In shunt relation with the tube is connected a a capacitor 44 which is normally charged to the full-tube energizing voltage. 'Ihe resistor 38 is connected between the cathode and grid element 46 of the actuating device control tube .24 and thereby impresses upon the tube grid a potential determined by the current iiow through this resistor.

In operation of the equipment just described, as long as no light is directed upon the photo tube 28, the negative grid bias impressed upon the gas-filled tube 32 maintains this tube nonconductive and thereby prevents current from flowing through resistor 38. This maintains the grid bias of tube 24 at such a value as to allow the tube to pass through the winding of the actuating device I8 a current suiicient to maintain the yoke member I6 in the illustrated position.

In the event that a can of odd size, as indicated at I4, is moved into register with the withdrawing yoke, the exposed bright surface thereof reflects light upon the photo tube which illumination raises the tube conductivity. The increase in current ilow through resistor 36 makes the grid bias ofv tube 32 sufficiently less negative to cause the tube to break down -and pass current between its major elements. In owing through resistor 38 this current sets up therein a voltage drop which makes the grid bias of tube 24 more negative and thereby reduces the current ow through the tube sufciently to render the solenoid I8 ineiective in holding the yoke in the illustrated position. As a result the spring 2 0 withdraws the yoke and the odd sized can therebeneath from the traveling conveyor I0.

In breaking down the tube 32 establishes between its major elements a discharge path for the capacitor 44. The capacitor potential is accordingly dissipated through this path in a very short time, the length oi which may be changed by varying the value of a resistor 45, at the expiration of which the voltage across the major elements of the tube 32 has been reduced to below the value required to maintain the tube conductive. 'I'he tube may thus be rendered non-conductive almost immediately. A recharging current is then supplied through resistor 38 to the capacitor. As the capacitor charges this current decreases until tube 24 has its grid bias restored nearly to the normal value at which solenoid I8 is energized with sufficient intensity to overcome the opposing force of spring 20 and restore the yoke I6 to the illustrated position. All of this takes place within an exceedingly brief space of time, which is less than that required for the next can in line on the conveyor to moveinto registering position with the yoke.

It will be apparent that the length of time required to render the tube 32 non-conductive and to recharge the capacitor 44 may be adjusted throughout a wide range by varying the relative sizes of the capacitor, the resistor 38 through which it derives charging current, and the resistor 45 through which the capacitor discharges. I

The improved timing scheme of my invention is not restricted to circuit combinations in which the photo tube must receive illumination to effect the desired control. It may, instead, as illustrated in Fig. 4, be applied to situations in which an interruption of a normally maintained light beam, as that which originates in lamp 26', will cause the photo tube 28 to decrease its conductivity and thereby eiect an appropriate change of current supplied to winding I8 of an actuating device. In the system of Fig. 4, the details of the equipment for interrupting the phototube light beam and the functioning of the actuating device have not been illustrated inasmuch as applications wherein such operation is desired are numerous and well known in the art.

The circuit combination of Fig.4 is identical with that of Fig. 1 with the exception that the photo tube is connected between the negative terminal of the source of potential 34 and the 'grid 42 of the electronic tube 32 and the resistor Fig. 4 is identical with that which has just beenv explained in connection with the Fig. 1.

Nor is it essential that the eiect of a control impulse initiated by the photo tube should decrease the current supplied to the actuating device winding I8. In Fig. 5 I have illustrated circuits so modiiied that the controlling impulse serves tov instead increase this current. This effect is obtained by reversing the connections to the major elements of the tube 24' and normally circuits of impressing upon the grid element 46 of this tube a bias sufficiently negative to practically discontinue tube conductivity. In the circuit illustrated, this bias is derived from a tap connection along the voltage dividing resistor 40.

As soon as the tube 32 is rendered conductive, the resulting current flow through resistor 38 makes the grid bias of tube 24' more positive and thereby allows the tube to pass through the actuating device winding I8" a current appropriate to effect operation thereof.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention is, therefore, not to be restricted except insofar as is necessitated by the prior art and by the scope of the appended claims.

I claim as my invention:

l. A control system comprising a photo-sensitive device, an electronic tube of the non-continuous control type adapted to be rendered conductive hy said device, a device operatively controlled by said tube, and means, comprising a capacitor connected in shunt relation with said tube, for restricting each of said conductive periods to a given length.

2. In a system comprising a gas-iilled gridcontrolled electronic tube, a source of unidirectional energizing voltage therefor, and means in the form of a photo-cell adapted to render said tube conductive, the combination of means for restricting each of said conductive periods to a given length comprising a capacitor connected in shunt relation with the tube and an impeder series connected between the tube and the capacitor.

3. In a system comprising an electronic tube of the non-continuous control type, a circuit for impressing a direct-'current voltage upon the tube, a resistor included in said circuit, apparatus operatively responsive to the voltage drop across said resistor, and a photo tube adapted to render said electronic tube conductive, the combination of a capacitor connected in shunt relation with said tube to restrict each oi its conductive periods to a given length.

4. In a system comprising an electronic tube having an anode, a cathode and a control grid, a source of unidirectionalv voltage, a circuit including a resistor for connecting said source to impress a unidirectional voltage across the tube, a connection including a resistor between one terminal of said source and the control grid, a capacitor connected in shunt relation to said tube, apparatus operatively responsive to the voltage drop across the iirst-named resistor, and a phototube for connecting the other terminal of said source to said grid i'or controlling current iiow through said tube and said ilrst-namedresistor.

5. In a system comprising an electronic tube having an anode, a cathode and a control grid, a source of unidirectional voltage, a circuit including a resistor for connecting said source to impress a unidirectional voltage across the tube, a connection including a resistor between one terminal of said source and the control grid, a capacitor connected in shunt relation to said tube, an electronic tube having a cathode and control grid connected to be responsive to the voltage drop across said resistor for controlling an electrical apparatus, and means for varying the control potential of the first-named tube for controlling current iiow therethrough.

6. In a system comprising an electronic tube having an anode, a cathode and a control grid, a source of unidirectional voltage, a circuit including a resistor for connecting said source to impress a unidirectional voltage across the tube, a connection including a resistor between one terminal of said source and the control grid, a capacitor connected in shunt relation to said tube. and a variable resistor in the circuit between said capacitor and said tube, apparatus operatively responsive to the voltage drop across the rstnamed resistor, and means for controlling the grid -potential for controlling current iiow through said tube and said mst-named resistor.

FINN H. GULLIRBEN. 

